James Toseland will retire from motorbike racing with immediate effect because of a wrist injury he sustained during a crash at Aragon, Spain in March.
The former double World Superbike champion published a letter on his personal website.
Toseland visited his consultant Mike Hayton this week and the diagnosis was the "worst [he] could have prepared [himself] for".
"The easiest way to explain it is that I don’t have enough range of movement in my wrist to race professionally and no amount of physiotherapy is going to improve that," he wrote.
"This all led to the verdict was that it’s no longer safe for me to continue a career in motorcycle racing."
The 31-year-old also crashed out of the most recent race in Germany and has said that the safety of himself and fellow riders is paramount.
Speaking of his fans, the Englishman added: "You have been amazing in the best and worst times of my career and it’s been almost like having a second family to support me through my career.
"So, thank you for everything and I hope that I have done you proud."
